1. Field of the Invention
The present invention relates to an improved LED lighting string employing a rectified and filtered device to rectify input AC source into DC source, and more particularly to an improved LED lighting string capable of improving LED's flickering issue and optimizing the optical power factor in LED lighting string.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, a current LED lighting string 10 decorated on a Christmas tree or on windows for celebration during the Christmas day or festival every year comprises an electrical wire 11 integrating with a plug 12 to get an AC source and one or more loops of LED lighting string 15 with a predetermined number of LED lamps 15a for lighting with single or multiple colors.
It is known a traditional bulb is workable during the positive and negative half-wave when to input AC source into the traditional bulb. While since the LED's characteristic is different from the traditional bulb the LED lamp can work during either positive or negative half-wave only.
Due to the LED having the characteristic of semiconductor, the LED lamps when to apply the AC power source fails to emit lighting during the positive half-wave and negative half-wave simultaneously. Thus, this flaw may cause LED lamp can only work during half-wave, eventually resulting in massive loss to power factor.
In a word, the current LED lighting string 10 shown in FIGS. 1 and 2 obviously exists with the flickering problem, which was mainly caused by the electrical frequency of 60 Hz or 50 Hz workable during either positive or negative half-wave of AC input source. The flickering problem existed in the current LED lighting string 10 will cause consumer with uncomfortable feeling in visual perception during the application.
For solving the flicking problem of the current LED lighting string 10 mentioned above, it needs to design an electrical circuit program to improve the current LED Lighting String in application.